The invention relates to a system for the elimination of radio interference which is disposed in a container filled with a casted insulating material. An inductor functioning as a choke is formed on a toroidal core of low-retentivity material. At least two windings permeated by line current are wound on the core and magnetically conductive material is disposed in the proximity of the choke.
An arrangement for the elimination of radio noise, and which contains a current-compensated multiple choke, is known from German Utility Model No. 70 37 848, incorporated herein by reference. There, at least two windings are applied to a toroidal core. These windings are permeated by the operating current in such manner that the magnetic effects of the operating current which flow back and forth are mutually cancelled in the toroidal core. By so doing, a high attenuation can be achieved for interference currents which are unbalanced-to-ground. This attenuation is subject to further improvement by employing capacitors disposed between the conductors and ground. Since balanced-to-ground interference currents cancel one another through their magnetic effect in the core like the operating currents, an increase of the leakage inductance of the noise suppression choke is provided for the attenuation of the balanced-to-ground currents. In order to increase this leakage inductance, the choke is disposed in a container consisting of electrically conductive material, and additional magnetically conductive parts are provided, if need be, below or in the center point of the toroidal core.